Real-World Performance of Large Vessel Occlusion Artificial Intelligence-Based Computer-Aided Triage and Notification Algorithms-What the Stroke Team Needs to Know.

PURPOSE: To evaluate the real-world performance of two FDA-approved artificial intelligence (AI)-based computer-aided triage and notification (CADt) detection devices and compare them with the manufacturer-reported performance testing in the instructions for use. MATERIALS AND METHODS: Clinical performance of two FDA-cleared CADt large-vessel occlusion (LVO) devices was retrospectively evaluated at two separate stroke centers. Consecutive "code stroke" CT angiography examinations were included and assessed for patient demographics, scanner manufacturer, presence or absence of CADt result, CADt result, and LVO in the internal carotid artery (ICA), horizontal middle cerebral artery (MCA) segment (M1), Sylvian MCA segments after the bifurcation (M2), precommunicating part of cerebral artery, postcommunicating part of the cerebral artery, vertebral artery, basilar artery vessel segments. The original radiology report served as the reference standard, and a study radiologist extracted the above data elements from the imaging examination and radiology report. RESULTS: At hospital A, the CADt algorithm manufacturer reports assessment of intracranial ICA and MCA with sensitivity of 97% and specificity of 95.6%. Real-world performance of 704 cases included 79 in which no CADt result was available. Sensitivity and specificity in ICA and M1 segments were 85.3% and 91.9%. Sensitivity decreased to 68.5% when M2 segments were included and to 59.9% when all proximal vessel segments were included. At hospital B the CADt algorithm manufacturer reports sensitivity of 87.8% and specificity of 89.6%, without specifying the vessel segments. Real-world performance of 642 cases included 20 cases in which no CADt result was available. Sensitivity and specificity in ICA and M1 segments were 90.7% and 97.9%. Sensitivity decreased to 76.4% when M2 segments were included and to 59.4% when all proximal vessel segments are included. DISCUSSION: Real-world testing of two CADt LVO detection algorithms identified gaps in the detection and communication of potentially treatable LVOs when considering vessels beyond the intracranial ICA and M1 segments and in cases with absent and uninterpretable data.

ACR's Connect and AI-LAB technical framework.

Objective: To develop a free, vendor-neutral software suite, the American College of Radiology (ACR) Connect, which serves as a platform for democratizing artificial intelligence (AI) for all individuals and institutions. Materials and Methods: Among its core capabilities, ACR Connect provides educational resources; tools for dataset annotation; model building and evaluation; and an interface for collaboration and federated learning across institutions without the need to move data off hospital premises. Results: The AI-LAB application within ACR Connect allows users to investigate AI models using their own local data while maintaining data security. The software enables non-technical users to participate in the evaluation and training of AI models as part of a larger, collaborative network. Discussion: Advancements in AI have transformed automated quantitative analysis for medical imaging. Despite the significant progress in research, AI is currently underutilized in current clinical workflows. The success of AI model development depends critically on the synergy between physicians who can drive clinical direction, data scientists who can design effective algorithms, and the availability of high-quality datasets. ACR Connect and AI-LAB provide a way to perform external validation as well as collaborative, distributed training. Conclusion: In order to create a collaborative AI ecosystem across clinical and technical domains, the ACR developed a platform that enables non-technical users to participate in education and model development.

Multi-Institutional Assessment and Crowdsourcing Evaluation of Deep Learning for Automated Classification of Breast Density.

OBJECTIVE: We developed deep learning algorithms to automatically assess BI-RADS breast density. METHODS: Using a large multi-institution patient cohort of 108,230 digital screening mammograms from the Digital Mammographic Imaging Screening Trial, we investigated the effect of data, model, and training parameters on overall model performance and provided crowdsourcing evaluation from the attendees of the ACR 2019 Annual Meeting. RESULTS: Our best-performing algorithm achieved good agreement with radiologists who were qualified interpreters of mammograms, with a four-class κ of 0.667. When training was performed with randomly sampled images from the data set versus sampling equal number of images from each density category, the model predictions were biased away from the low-prevalence categories such as extremely dense breasts. The net result was an increase in sensitivity and a decrease in specificity for predicting dense breasts for equal class compared with random sampling. We also found that the performance of the model degrades when we evaluate on digital mammography data formats that differ from the one that we trained on, emphasizing the importance of multi-institutional training sets. Lastly, we showed that crowdsourced annotations, including those from attendees who routinely read mammograms, had higher agreement with our algorithm than with the original interpreting radiologists. CONCLUSION: We demonstrated the possible parameters that can influence the performance of the model and how crowdsourcing can be used for evaluation. This study was performed in tandem with the development of the ACR AI-LAB, a platform for democratizing artificial intelligence.

U.S. Diagnostic Reference Levels and Achievable Doses for 10 Adult CT Examinations.

Purpose To develop diagnostic reference levels (DRLs) and achievable doses (ADs) for the 10 most common adult computed tomographic (CT) examinations in the United States as a function of patient size by using the CT Dose Index Registry. Materials and Methods Data from the 10 most commonly performed adult CT head, neck, and body examinations from 583 facilities were analyzed. For head examinations, the lateral thickness was used as an indicator of patient size; for neck and body examinations, water-equivalent diameter was used. Data from 1 310 727 examinations (analyzed by using SAS 9.3) provided median values, as well as means and 25th and 75th (DRL) percentiles for volume CT dose index (CTDIvol), dose-length product (DLP), and size-specific dose estimate (SSDE). Applicable results were compared with DRLs from eight countries. Results More than 46% of the facilities were community hospitals; 13% were academic facilities. More than 48% were in metropolitan areas, 39% were suburban, and 13% were rural. More than 50% of the facilities performed fewer than 500 examinations per month. The abdomen and pelvis was the most frequently performed examination in the study (45%). For body examinations, DRLs (75th percentile) and ADs (median) for CTDIvol, SSDE, and DLP increased consistently with the patient's size (water-equivalent diameter). The relationships between patient size and DRLs and ADs were not as strong for head and neck examinations. These results agree well with the data from other countries. Conclusion DRLs and ADs as a function of patient size were developed for the 10 most common adult CT examinations performed in the United States. © RSNA, 2017.

Diagnostic reference ranges for pediatric abdominal CT.

PURPOSE: To develop diagnostic reference ranges (DRRs) and a method for an individual practice to calculate site-specific reference doses for computed tomographic (CT) scans of the abdomen or abdomen and pelvis in children on the basis of body width (BW). MATERIALS AND METHODS: This HIPAA-compliant multicenter retrospective study was approved by institutional review boards of participating institutions; informed consent was waived. In 939 pediatric patients, CT doses were reviewed in 499 (53%) male and 440 (47%) female patients (mean age, 10 years). Doses were from 954 scans obtained from September 1 to December 1, 2009, through Quality Improvement Registry for CT Scans in Children within the National Radiology Data Registry, American College of Radiology. Size-specific dose estimate (SSDE), a dose estimate based on BW, CT dose index, dose-length product, and effective dose were analyzed. BW measurement was obtained with electronic calipers from the axial image at the splenic vein level after completion of the CT scan. An adult-sized patient was defined as a patient with BW of 34 cm. An appropriate dose range for each DRR was developed by reviewing image quality on a subset of CT scans through comparison with a five-point visual reference scale with increments of added simulated quantum mottle and by determining DRR to establish lower and upper bounds for each range. RESULTS: For 954 scans, DRRs (SSDEs) were 5.8-12.0, 7.3-12.2, 7.6-13.4, 9.8-16.4, and 13.1-19.0 mGy for BWs less than 15, 15-19, 20-24, 25-29, and 30 cm or greater, respectively. The fractions of adult doses, adult SSDEs, used within the consortium for patients with BWs of 10, 14, 18, 22, 26, and 30 cm were 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9, respectively. CONCLUSION: The concept of DRRs addresses the balance between the patient's risk (radiation dose) and benefit (diagnostic image quality). Calculation of reference doses as a function of BW for an individual practice provides a tool to help develop site-specific CT protocols that help manage pediatric patient radiation doses.

Examining the economic costs related to lifestyle and pharmacological interventions in youth with Type 2 diabetes.

The best treatment option for children with Type 2 diabetes has not yet been established. The Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study is currently testing the efficacy of three therapies: metformin, metformin plus rosiglitazone and metformin plus an intensive lifestyle intervention. The relative cost-effectiveness of these therapies is also being examined. This review discusses the rationale for the design and methods applied in the economic analysis. The design of the economic analysis in the TODAY study was influenced by the existing literature and two primary study parameters: the nature of the interventions and the participants' age. The lifestyle intervention is an intensive behavioral intervention comprising diet and physical activity. Since economic factors influence both diet and physical activity, the analytical plan includes measurement of food and exercise-related purchases. Due to the young age of the participants, the impact of the intervention on adult caregivers is also included in the analysis. This analysis focuses on the time spent by the caregivers in both medical treatment and nutrition- and activity-related activities, and the value of this time relative to usual activities. Important methodological questions include how and when to collect information, not only on medical costs, but also on the impact of caregiver time, travel, food and equipment purchases. In the TODAY study, these latter resources are being measured by regularly administered surveys completed by the caregivers. The approach to the cost-effectiveness assessment undertaken by the TODAY study is one of the first in diabetes research to focus on youth and to include a societal perspective, regular and prospective assessment of clinician and caregiver time, and a comprehensive assessment of the costs associated with lifestyle behaviors. It can serve as a model for future studies of diabetes treatments.

The evaluation of treatment when center-specific selection criteria vary with respect to patient risk.

Many standards of medical care are based on the demonstrated effects of various treatment strategies or processes. Unlike pharmacological treatments, these strategies or processes are not necessarily subjected to rigorous clinical trials and their benefit is frequently assessed from observational data. For evaluating the influence of such medical processes on patient outcomes, not only is risk adjustment an issue, but also the "center effect" represents an important, often overlooked consideration. Both the quality of care and the tendency to use certain treatments or processes vary from one center to another. The induced similarity in outcomes within center, as well as the potential for confounding by center, needs to be addressed within the context of risk adjustment. In addition, center-specific selection criteria for a treatment strategy can vary with respect to patient risk. Because of these considerations, it is important to adequately separate the within-center effects of the treatment or strategy from the across-center effects, which relate more to center performance. The primary objective of this article is to explore and extend current methods of dealing with center confounding for dichotomous outcomes, primarily for the situation where selection on the basis of patient risk can vary from center to center. A simulation study compares results from several different analytic methods and provides evidence for the importance of considering confounding due to both risk and center when evaluating the effectiveness of a process. An example that examines the effect of early extubation after bypass surgery is also presented.

Selecting patients with mitral regurgitation and left ventricular dysfunction for isolated mitral valve surgery.

BACKGROUND: American College of Cardiology/American Heart Association (ACC/AHA) Guidelines state that patients with an ejection fraction (EF) of 30% or less should not undergo mitral valve replacement for mitral regurgitation (MR). We sought to establish, using a national cardiac surgery database, whether patients with left ventricular dysfunction may safely undergo mitral valve surgery for MR, and if so, which ones. METHODS: We queried the Society of Thoracic Surgeons (STS) National Database to identify patients who had isolated mitral valve replacement or repair for MR between 1998 and 2001. Mortality and morbidity outcomes were compared by EF category (< or = 30% vs > 30%), and observed mortality compared by EF group, stratified by predicted risk for mortality. A classification and regression tree (CART) model was then used to determine which patient characteristics contributed most to designate the high-risk patient. RESULTS: Of the 14,582 patients who had mitral valve surgery, 727 had an EF of 30% or less and 13,855 had an EF of more than 30%. Observed mortality rates were higher for patients with an EF of 30% or less (5.4% vs 3.1%). However, for low-risk to medium-risk patients, mortality rates remained fairly constant across levels of EF. Mortality is notably increased in the high-risk patients (predicted risk > 10%). A classification tree identifies three key characteristics for high risk: age more than 75 years, renal failure, and emergent or salvage procedure. CONCLUSIONS: When the predicted mortality risk is less than 10%, EF has minimal impact on operative mortality for mitral regurgitation. In contrast to the ACC/AHA Guidelines, our data show that operative risk for mitral valve surgery is not prohibitive for most patients with ventricular dysfunction.

Odds ratios for a continuous outcome variable without dichotomizing.

The loss of information from dichotomizing a continuous outcome is well documented in the literature. One advantage of dichotomizing is that it allows estimation of odds ratio parameters through a logistic regression analysis. The objective of this paper is to develop a new estimator of the same odds ratio parameters through regression analysis on the original continuous outcome without the inherent loss of information caused by dichotomizing. Through a mathematical, asymptotic development the relative sample sizes required to attain a specified power when testing the odds ratio parameter are compared for the dichotomizing procedure and the proposed approach. The comparison highlights the substantial sample size savings attained by the proposed approach, particularly for large values of the odds ratio parameter and for small proportions of dichotomized successes or failures. In a Monte Carlo simulation the variances and absolute biases of the two odds ratio estimators and the length of their respective confidence intervals again demonstrate the improvement attained by the proposed approach. In addition, coverage probabilities of the confidence intervals of the proposed approach converge quickly to the nominal levels. The cost savings due to the reduction in required sample size when using this method make it a very attractive study design and analysis tool for medical researchers.

Procedural volume as a marker of quality for CABG surgery.

CONTEXT: There have been recent calls for using hospital procedural volume as a quality indicator for coronary artery bypass graft (CABG) surgery, but further research into analysis and policy implication is needed before hospital procedural volume is accepted as a standard quality metric. OBJECTIVE: To examine the contemporary association between hospital CABG procedure volume and outcome in a large national clinical database. DESIGN, SETTING, AND PARTICIPANTS: Observational analysis of 267 089 isolated CABG procedures performed at 439 US hospitals participating in the Society of Thoracic Surgeons National Cardiac Database between January 1, 2000, and December 31, 2001. MAIN OUTCOME MEASURE: Association between hospital CABG procedural volume and all-cause operative mortality (in-hospital or 30-day, whichever was longer). RESULTS: The median (interquartile range) annual hospital-isolated CABG volume was 253 (165-417) procedures, with 82% of centers performing fewer than 500 procedures per year. The overall operative mortality was 2.66%. After adjusting for patient risk and clustering effects, rates of operative mortality decreased with increasing hospital CABG volume (0.07% for every 100 additional CABG procedures; adjusted odds ratio [OR], 0.98; 95% confidence interval [CI], 0.96-0.99; P =.004). While the association between volume and outcome was statistically significant overall, this association was not observed in patients younger than 65 years or in those at low operative risk and was confounded by surgeon volume. The ability of hospital volume to discriminate those centers with significantly better or worse mortality was limited due to the wide variability in risk-adjusted mortality among hospitals with similar volume. Closure of up to 100 of the lowest-volume centers (ie, those performing < or =150 CABG procedures/year) was estimated to avert fewer than 50 of 7110 (<1% of total) CABG-related deaths. CONCLUSION: In contemporary practice, hospital procedural volume is only modestly associated with CABG outcomes and therefore may not be an adequate quality metric for CABG surgery.

Patient selection and current practice strategy for off-pump coronary artery bypass surgery.

OBJECTIVE: Previous studies comparing off-pump coronary artery bypass surgery (OPCABG) to conventional techniques utilizing cardiopulmonary bypass (CABG-CPB) have failed to provide patient selection guidelines. We sought to determine guidelines, attempting to rectify the limitations of previous studies. METHODS AND RESULTS: A retrospective analysis of prospectively collected data from the Society of Thoracic Surgeons National Database, from January 1999 through December 2000, identified 204 602 multivessel coronary artery bypass (CABG) patients. Unadjusted and risk-adjusted odds ratios (OR) were calculated to compare OPCABG and CABG-CPB morbidity and mortality. A propensity model was developed to identify factors associated with selection for OPCABG. All off-pump patients were pair-matched with on-pump patients based on their propensity to receive an off-pump procedure. Off-pump patients, 8.8% of the total, had significantly different patient characteristics than the on-pump group. Characteristics associated with OPCABG selection included fewer diseased vessels, absence of left main disease, fewer bypass grafts, no previous CABG, older age, chronic lung disease, and renal failure. Unadjusted and risk-adjusted odds ratios indicate a significant off-pump survival benefit and decreased morbidity including stroke and renal failure in the overall group. Propensity matching also showed a significant OPCABG survival benefit [OR (95% CI) 0.83 (0.72, 0.96)]. Subgroup analysis of propensity-matched groups identified off-pump survival benefits in patients with previous CABG (OR=0.53), diabetics (OR=0.66), LVEF between 30% to 50% (OR=0.75), females (OR=0.79), and age 66 to 75 years (OR=0.80). CONCLUSIONS: OPCABG imparts some survival benefit to most patient subgroups. Higher risk patients including those undergoing reoperative CABG, diabetics, and the elderly may gain the most benefit.

Cardiac surgery in nonagenarians and centenarians.

BACKGROUND: Nonagenarians and centenarians are a rapidly growing segment of the population. No previous study has used a national database to compare outcomes in these patients to those of other groups undergoing cardiac surgical procedures. STUDY DESIGN: The Society of Thoracic Surgeons National Database was used to review retrospectively 662,033 patients (5 patients more than 100 years of age; 1,092 patients 90 to 99 years; 59,576 patients 80 to 89 years; and 621,360 patients 50 to 79 years of age) who underwent cardiac surgical procedures from 1997 through 2000. These included 575,389 patients who had undergone coronary artery bypass grafting (CABG) only; 56,915 patients with CABG and concomitant mitral or aortic valve replacement or repair (CABG+VALVE); and 49,729 patients with mitral or aortic valve repair or replacement only (VALVE-only). A multivariate logistic regression model was developed to examine predictors of operative mortality in patients more than 90 years of age. RESULTS: For CABG-only patients, operative mortality was 11.8% for patients more than 90 years of age, 7.1% for those 80 to 89 years, and 2.8% for those 50 to 79 years. The incidence of renal failure and prolonged ventilation was highest among patients more than 90 years of age (9.2% and 12.2%), compared with those 80 to 89 years (7.7% and 10.5%) or 50 to 79 years (3.5% and 6.0%). For VALVE-only patients and CABG+VALVE patients operative mortality for those more than 90 years of age was 11.4% and 12.0%, respectively, compared with 8.3% and 11.5% for those 80 to 89 years and 4.3% and 7.6% for those 50 to 79 years. The major preoperative risk factors for operative mortality among patients more than 90 years of age undergoing isolated CABG were as follows (C-index, 0.68): emergent/salvage: odds ratio, 2.26; 95% confidence interval, 1.38-3.69; preoperative intraaortic balloon pump: odds ratio, 2.79; 95% confidence interval, 1.47-5.32; renal failure: odds ratio, 2.08; 95% confidence interval, 1.12-3.86; peripheral vascular disease or cerebrovascular vascular disease: odds ratio, 1.39, 95% confidence interval, 0.96-2.02; mitral insufficiency: odds ratio, 1.50; 95% confidence interval, 0.93-2.41. Approximately 57% of the nonagenarians and centenarians lacked any of the first four risk factors and had an operative mortality of 7.2%. CONCLUSIONS: Operative mortality and complication rates associated with cardiac surgical procedures are highest for nonagenarians and centenarians. But with careful patient selection, a majority of these patients have a lower risk of CABG-related mortality approaching that of younger patients.

Use of continuous quality improvement to increase use of process measures in patients undergoing coronary artery bypass graft surgery: a randomized controlled trial.

CONTEXT: A rigorous evaluation of continuous quality improvement (CQI) in medical practice has not been carried out on a national scale. OBJECTIVE: To test whether low-intensity CQI interventions can be used to speed the national adoption of 2 coronary artery bypass graft (CABG) surgery process-of-care measures: preoperative beta-blockade therapy and internal mammary artery (IMA) grafting in patients 75 years or older. DESIGN, SETTING, AND PARTICIPANTS: Three hundred fifty-nine academic and nonacademic hospitals (treating 267 917 patients using CABG surgery) participating in the Society of Thoracic Surgeons National Cardiac Database between January 2000 and July 2002 were randomized to a control arm or to 1 of 2 groups that used CQI interventions designed to increase use of the process-of-care measures. INTERVENTION: Each intervention group received measure-specific information, including a call to action to a physician leader; educational products; and periodic longitudinal, nationally benchmarked, site-specific feedback. MAIN OUTCOME MEASURE: Differential incorporation of the targeted care processes into practice at the intervention sites vs the control sites, assessed by measuring preintervention (January-December 2000)/postintervention (January 2001-July 2002) site differences and by using a hierarchical patient-level analysis. RESULTS: From January 2000 to July 2002, use of both process measures increased nationally (beta-blockade, 60.0%-65.6%; IMA grafting, 76.2%-82.8%). Use of beta-blockade increased significantly more at beta-blockade intervention sites (7.3% [SD, 12.8%]) vs control sites (3.6% [SD, 11.5%]) in the preintervention/postintervention (P =.04) and hierarchical analyses (P<.001). Use of IMA grafting also tended to increase at IMA intervention sites (8.7% [SD, 17.5%]) vs control sites (5.4% [SD,15.8%]) (P =.20 and P =.11 for preintervention/postintervention and hierarchical analyses, respectively). Both interventions tended to have more impact at lower-volume CABG sites (for interaction: P =.04 for beta-blockade; P =.02 for IMA grafting). CONCLUSIONS: A multifaceted, physician-led, low-intensity CQI effort can improve the adoption of care processes into national practice within the context of a medical specialty society infrastructure.

The Society of Thoracic Surgeons: 30-day operative mortality and morbidity risk models.

BACKGROUND: Although 30 day risk-adjusted operative mortality (ROM) has been used for quality assessment, it is not sufficient to describe the outcomes after coronary artery bypass grafting (CABG) surgery. Risk-adjusted major morbidity may differentially impact quality of care (as complications occur more frequently than death) and enhance a surgical team's ability to assess their quality. This study identified the preoperative risk factors associated with several complications and a composite outcome (the presence of any major morbidity or 30-day operative mortality or both). METHODS: For CABG procedures, the 1997 to 1999 Society of Thoracic Surgeons (STS) National Adult Cardiac Surgery Database was used to develop ROM and risk-adjusted morbidity (ROMB) models. Risk factors were selected using standard STS univariate screening and multivariate logistic regression approaches. Risk model performance was assessed. Across STS participating sites, the association of observed-to-expected (O/E) ratios for ROM and ROMB was evaluated. RESULTS: The 30-day operative death and major complication rates for STS CABG procedures were 3.05% and 13.40%, respectively (503,478 CABG procedures), including stroke (1.63%), renal failure (3.53%), reoperation (5.17%), prolonged ventilation (5.96%), and sternal infection (0.63%). Risk models were developed (c-indexes for stroke [0.72], renal failure [0.76], reoperation [0.64], prolonged ventilation [0.75], sternal infection [0.66], and the composite endpoint [0.71]). Only a slight correlation was found, however, between ROMB and ROM indicators. CONCLUSIONS: Used in combination, ROMB and ROM may provide the surgical team with additional information to evaluate the quality of their care as well as valuable insights to allow them to focus on areas for improvement.

Effect of cardiac rehabilitation on functional outcomes after coronary revascularization.

BACKGROUND: Current guidelines recommending cardiac rehabilitation (CR) after coronary revascularization are largely based on early studies that evaluated only a subset of the population and failed to assess the impact of CR on a patient's perception of their functional status. The main objective of this study was to evaluate the impact of CR in a diverse contemporary population on patient functional outcomes. METHODS: We studied the effect of CR on 6-month SF-36 Physical Functioning (PF) in 700 patients (mean age 67 +/- 11 years, 37% women) who underwent coronary bypass grafting or percutaneous intervention from August 1998 to July 2000. RESULTS: Overall CR participation was 24%. At baseline, CR participants had higher PF (mean 62.5 vs 52.5, P <.001). After adjusting for baseline clinical variables and PF score, CR was associated with significant improvement in 6-month PF (+5.0, 95% CI 1.0-9.0). This improvement was observed in all patient subgroups, but tended to be greater in magnitude in men versus women, patients aged <70 years versus > or =70 years, and patients with coronary bypass grafting versus patients with percutaneous intervention. CR participants also tended to be more likely to engage in regular exercise (63% vs 55%, P =.06) and modify their diet (82% vs 73%, P =.07). Rates of rehospitalization and repeat revascularization were similar among CR participants and nonparticipants. CONCLUSIONS: CR after coronary revascularization is associated with improved functional outcomes and adoption of secondary preventive measures. Innovative strategies to facilitate CR enrollment and tailoring programs to better address the needs of all patient subgroups would extend these benefits to more eligible patients.

Influence of age on outcomes in patients undergoing mitral valve replacement.

BACKGROUND: Although increasing age has been associated with greater risk of mortality for patients undergoing mitral valve replacement, it is less clear whether this elevated risk is related to age-related differences in comorbidity or other clinical characteristics. METHODS: A population of 31,688 patients from The Society of Thoracic Surgeons National Cardiac Database undergoing mitral valve replacement either alone or in combination with coronary artery bypass grafting or tricuspid surgical procedures from 1997 to 2000 was examined to assess age-related variation in clinical features, morbidity, and mortality. Multivariable logistic regression was used to determine the effect of age after adjusting for other known risk factors. A classification tree was used to identify low-risk elderly (> or = 75 years) patients. RESULTS: Operative mortality increased four-fold from 4.1% in patients aged less than 50 years up to 17.0% in patients aged 80 years or more. Similarly, major operative complications (stroke, prolonged ventilation, reoperation for bleeding, renal failure, and sternal infection) also increased with age, rising from 13.5% (age < 50 years) to 35.5% (age > or = 80 years). Multivariable adjustment attenuated the odds of operative mortality, but age remained a significant risk factor. After adjusting for other patient risk factors, age accounted for 13% and 10% of the explainable risk for mortality and morbidity, respectively. Among the elderly, four variables (hemodynamic instability, New York Heart Association class IV, renal failure, and concomitant coronary artery bypass grafting) were identified to distinguish levels of risk, from operative mortality rates exceeding 31% to those with 7.7% mortality. CONCLUSIONS: Operative mortality and morbidity rise with increasing age of patients undergoing mitral valve replacement. Although this excess risk is partially a result of increased comorbid burden and other operative factors, age remains an independent powerful risk factor for operative risk for mitral valve replacement. Understanding the relationship of age with other risk factors for mitral valve replacement can help stratify risk, enabling physicians to identify lower risk patients.

The risks of moderate and extreme obesity for coronary artery bypass grafting outcomes: a study from the Society of Thoracic Surgeons' database.

BACKGROUND: Obesity is epidemic in the United States and afflicts 97 million adults. Prior single center studies have been contradictory as to obese patients having higher risks with coronary artery bypass operations. Our objective was to assess the independent effect of both moderate (body mass index [BMI], 35 to 39.9) and extreme (BMI > or = 40) obesity on bypass operation outcomes using the Society of Thoracic Surgeons National Cardiac Database. METHODS: The study population consisted of 559,004 patients from the Society of Thoracic Surgeons database who underwent first-time, isolated coronary artery bypass grafting between January 1997 and December 2000. We compared 42,060 moderately obese patients (BMI, 35 to 39.9) and 18,735 extremely obese patients (BMI > or = 40) with 498,209 normal or mildly obese patients (BMI, 18.5 to 34.9). Multivariable logistic regression was used to determine whether BMI subgroups were independent predictors of operative risk after adjusting for other preoperative factors. RESULTS: Compared with normal or mildly obese patients (BMI, 18.5 to 34.9), moderate and severely obese patients were younger and more likely to be diabetic and hypertensive. After adjusting for these and other known preoperative risk factors, moderate obesity slightly elevated patients' operative risk (adjusted odds ratio, 1.21; confidence interval, 1.13 to 1.29). In contrast, extremely obese patients had marked higher risk for operative mortality (adjusted odds ratio, 1.58; confidence interval, 1.45 to 1.73). Major perioperative complications, particularly deep sternal wound infection, renal failure, and prolonged postoperative hospital stay also increased for extremely obese patients. CONCLUSIONS: Extreme obesity (body mass index > or = 40) is a significant independent predictor for adverse outcomes and prolonged hospitalization after coronary artery bypass operation.